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From Samuel Rash <sl.r...@fb.com>
Subject Re: performance of watches
Date Fri, 17 Dec 2010 04:23:25 GMT
Yea--one host going down should trigger 24k watches.  Each host then looks
at its load and determines which paths to acquire (they represent traffic
flow).  This could result in, at worst, 24k create() attempts immediately

I'll read the docs--Thanks


On 12/16/10 8:06 PM, "Mahadev Konar" <mahadev@yahoo-inc.com> wrote:

>Hi Sam,
> Just a clarifiaction, will a host going down fire 625 * 39 watches? That
>is ~ 24000 watches per host being down.
>You can take a look at
>http://wiki.apache.org/hadoop/ZooKeeper/ServiceLatencyOverview about
>watches and latencies and hw requirements. Please do take a look and if
>it doesn't answer your questions, we should add more documentation.
>On 12/16/10 7:42 PM, "Samuel Rash" <sl.rash@fb.com> wrote:
>I am looking to run about 40 zookeeper clients with the following watch
>1. Up to 25,000 paths that every host has a watch on (each path has one
>child and the watch is one for that child, an ephemeral node, being
>2. An individual host "owns" 625 of these paths in this example; one going
>down will fire 625 watches to the other 39 hosts
>Is there any limit on the rate at which these watches can be sent off?
>What's the right size cluster? (3? 5?)  Does it need to be dedicated hw?

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